Despite advanced in early detection and aggressive adjuvant endocrine therapy, recurrence and metastasis of estrogen-receptor (ER)- positive breast cancer remains a problem, with a substantial proportion of patients relapsing years after diagnosis. Biologically, these tumors are primarily of the luminal subtype, amenable to anti-estrogen strategies that can control disease growth and limit metastatic spread. However, resistance and progression are universal, and patients will eventually stop responding to endocrine approaches. Advances in our understanding of luminal breast cancer biology, metastatic progression and endocrine resistance have led to new approaches and additional targets for intervention. Most important among these are interactions between ER signaling pathways and cell cycle control mechanisms or PI3K/mTor signaling, leading to new strategies incorporating cyclin-dependent kinase (cdk) and mTOR inhibitors, respectively, into endocrine therapy. While successful, many questions remain unanswered regarding optimal combinations and sequencing of these agents in specific populations, and management at the time of progression. This session will address (1) the evidence supporting the use of cdk 4/6 and mTOR inhibitors in standard practice for luminal advanced breast cancer, including agent selection and management of toxicity, (2) current understanding of resistance mechanisms and (3) next generation clinical trials designed to address resistance and improve outcomes in women with luminal advanced breast cancer.

Citation Format: DeMichele AM. Luminal ABC: optimal use of all available options? [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr ES11-1.